Clinical Features

• Peaks 5-15 years old in winter and early spring
• In children <3 yo, exudative strep pharyngitis is rare, infection more commonly presents as coryza, excoriat­ed nares, and generalized adenopathy
• "Scarlet fever" occasionally accompanies strep pharyngitis and appears as a finely papular erythematous rash that spares the face, may be accentuated in skin folds, and may desquamate during convalescence
• Severe unilateral pain or swallowing difficulty should raise concern about a local complication (e.g. periton­sillar or retropharyngeal abscess), particularly if the symptoms arise or progress several days into the illness

Score----	Likelihood of positive Group A Strep throat culture----
≤0	1-2.5%
1	5-10%
2	11-17%
3	28-35%
≥4	51-53%

Differential Diagnosis

• Cough, runny nose/congestion, and conjunctivitis are not typical symptoms of strep pharyngitis, and, if present, they suggest an alternative cause

• Periodic fever, aphthous stomatitis, pharyngitis and adenitis (PFAPA) syndrome - important non-infectious cause, occurs primarily <5 years old, episodes usually <5 days, recur at regular intervals of 3-6 weeks, and includes acute fever, pharyngitis plus tender cervical LAD, or aphthous ulcers.

Testing

• Rapid strep antigen­ detection test of a throat­ swab specimen - sensitivity 70-90%, specificity 95%, immediate results
• Throat culture - more sensitive and specific than rapid test but requires 1-2 days for results
• Serum antibodies to streptolysin O or DNase B
  • Useful for retrospective diagnosis of strep infection in cases of acute rheumatic fever or poststrep­ glomerulonephritis
  • Titers do not begin to increase until 7-14 days after the onset of infection, peak in 3-4 weeks
    
    
• Consider evaluation for infectious mononucleosis (EBV) due to significant overlap
  • EBV titers
  • Monospot (heterophile IgM)
    • Negative in 50-75% of children <12 years old with EBV, good sensitivity (85%) and specificity (94%) in older children
    • Monospot typically negative with other causes of infectious mono (CMV, HHV-6, HIV, Toxoplasma gondii)
  • CBC with differential - atypical lymphocytes of ≥10% on a peripheral-blood smear has a sensitivity of 75% and a specificity of 92% for the diagnosis of infectious mono

• Note:
  • In the absence of clinical findings of infection, a positive culture or rapid test is likely due to incidental carriage of strep
  • Strep can be cultured during winter months in ~10% of healthy school­ age children (less frequently in persons in other age groups). Carriage can persist for weeks or months and is associated with a very low risk of complications or transmission to others.

Treatment

Supportive care

• Rest, fluids, acetaminophen or ibuprofen for pain, gargle salt water, etc.

Antibiotics

• Self-limited in most cases even without antibiotics, but treatment reduces risk of subsequent acute rheumatic fever and development of local abscesses

Recurrent Strep

• Recurrence despite treatment
  • Repeat testing and treatment (if tests positive) are indicated
  • Recurrence may result from reinfec­tion from a household contact who is a carrier. Many experts rec­ommend throat cultures from household contacts and treatment of all carriers if reinfection is suspected.
  • Clindamycin and cepha­losporins appear to be more effective than peni­cillin in eradicating carriage, and these agents are preferred in this situation.
  • Strep can persist for days on toothbrushes but effectiveness of replacing brushes is unknown. There is no convincing evidence that household pets are a source of recurrent infection.

• Tonsillectomy indicated in certain cases

References